全角转半角

public String Convert全角to半角(String str)
        {
            StringBuilder sb = new StringBuilder(str);

            String str全角 = "１２３４５６７８９０，．（）＋－×％ａｂｃｄｅｆｇｈｉｊｋｌｍｎｏｐｑｒｓｔｕｖｗｘｙｚＡＢＣＤＥＦＧＨＩＪＫＬＭＮＯＰＱＲＳＴＵＶＷＸＹＺ";
            String str半角 = "1234567890,.()+-*%abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";

            for (int i = 0; i < str全角.Length; i++)
            {
                sb.Replace(str全角[i], str半角[i]);
            }

            return sb.ToString();
        }